aHigher rank coals are coals with gross calorific value (maf) of >24 MJ/kg, and those with gross calorific value (maf) of <24 MJ/kg provided mean random vitrinitic reflectance >0.6%. To convert from MJ/kg to Btu/lb, multiply by 429.23. b A reflectogram as characterized by code number 2 can also result from a high rank seam coal. cIt should be noted that some of the inertinite may be reactive.

^ Where the ash content of the coal is more than 10%, it must be reduced before analysis to below 10% by dense medium separation. In these cases, the cutting density and resulting ash content should be noted.

Source: Van Krevelen, D. W., Coal: Typology-Physics-Chemistry-Constitution, Third ed., Elsevier Science, Amsterdam, 1993. With permission.

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